
#include "apue.h"
#include <netdb.h>
#include <errno.h>
#include <syslog.h>
#include <sys/socket.h>

#define BUFLEN 128
#define QLEN 10

#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 256
#endif

extern int initserver(int, const struct sockaddr *, socklen_t, int);

void serve(int sockfd)
{
    int clfd, status;
    pid_t pid;

    set_cloexec(sockfd);
    while (1)
    {
        if ((clfd = accept(sockfd, NULL, NULL)) < 0)
        {
            syslog(LOG_ERR, "ruptimed: accept error: %s", strerror(errno));
            exit(1);
        }

        if ((pid = fork()) < 0)
        {
            syslog(LOG_ERR, "ruptimed: fork error: %s", strerror(errno));
            exit(1);
        }
        else if (0 == pid)
        {
            // The parent called daemonize ({Prog daemoninit}), so
            // STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO
            // are alread open to /dev/null. Thus the call to
            // close doesn't need to be protected by checks that
            // clfd isn't alread equal to one of these values
            if (dup2(clfd, STDOUT_FILENO) != STDOUT_FILENO ||
                dup2(clfd, STDERR_FILENO) != STDERR_FILENO)
            {
                syslog(LOG_ERR, "ruptimed: unexpected error");
                exit(1);
            }
            close(clfd);
            execl("/usr/bin/uptime", "uptime", (char *)0);
            syslog(LOG_ERR, "rupteimed: unexpected return from exec: %s", strerror(errno));
        }
        else
        {
            close(clfd);
            waitpid(pid, &status, 0);
        }
    }
}

int main(int argc, char *argv[])
{
    struct addrinfo *ailist, *aip;
    struct addrinfo hint;
    int sockfd, err, n;
    char *host;

    if (1 != argc)
    {
        err_quit("usage: ruptimed");
    }

    if ((n = sysconf(_SC_HOST_NAME_MAX)) < 0)
    {
        n = HOST_NAME_MAX;
    }

    if ((host = malloc(n)) == NULL)
    {
        err_sys("malloc error");
    }

    if (gethostname(host, n) < 0)
    {
        err_sys("gethostname error");
    }

    daemonize("ruptimed");
    memset(&hint, 0, sizeof(hint));
    hint.ai_flags = AI_CANONNAME;
    hint.ai_socktype = SOCK_STREAM;
    hint.ai_canonname = NULL;
    hint.ai_addr = NULL;
    hint.ai_next = NULL;

    if ((err = getaddrinfo(host, "ruptime", &hint, &ailist)) != 0)
    {
        syslog(LOG_ERR, "ruptimed: getaddrinfo error: %s", gai_strerror(err));
        exit(1);
    }

    for (aip = ailist; aip != NULL; aip = aip->ai_next)
    {
        if ((sockfd = initserver(SOCK_STREAM, aip->ai_addr, aip->ai_addrlen, QLEN)) >= 0)
        {
            serve(sockfd);
            exit(0);
        }
    }

    exit(1);
}
